1. Field of the invention
The present invention relates to an improved process for the production of polyaniline derivatives soluble in organic solvents.
2. Description of the Related Art
Investigation has been conducted in recent years with a view toward applying polyanilines as new electronic materials or electroconductive materials in a wide variety of fields such as cell electrode materials, antistatic materials, electromagnetic shielding materials, functional devices--e.g., photoelectric transducers, optical memories and various sensors--, display devices, various hybrid materials, transparent electroconductors, and various terminal equipment.
Polyanilines however have a highly developed .pi.-conjugated system. They are hence accompanied by the serious drawbacks that they are insoluble in most organic solvents and do not melt even when heated due to having a rigid main chain and the existence of strong interaction and many strong hydrogen bonds between polymer chains and also have poor moldability and permit neither cast molding nor coating.
They are therefore formed, for example, into electroconductive composite materials by impregnating base materials of a desired shape--such as fibers, porous bodies or the like of high-molecular materials--with their corresponding aniline monomers and then bringing the monomers into contact with a suitable polymerization catalyst or subjecting the monomers to electropolymerization to polymerize the monomers. As an alternative, such aniline monomers are polymerized in the presence of powder of a thermoplastic polymer to obtain similar composite materials.
In the meantime, polyanilines soluble in N-methyl-2-pyrrolidone alone have also been synthesizedby suitably choosing the polymerizaiton catalyst and reaction temperature [M. Abe et al.: J. Chem. Soc.,Chem. Commun., 1736 (1989)]. These polyanilines are however practically insoluble in other general organic solvents so that their application filed is limited.
To produce an N-Hydrocarbyl-substituted polyaniline, it has heretofore been known to homopolymerize an N-hydrocarbyl-substituted aniline or to copolymerize aniline with an N-hydrocarbyl-substituted aniline. These processes however involve the problems that the polymerization degree of the resultant N-hydrocarbyl-substituted polyaniline is low and the content of hydrocarbon groups can hardly be increased.